Liquid fuel compositions

ABSTRACT

The present invention provides a liquid fuel composition comprising:
         a) a liquid base fuel suitable for use in an internal combustion engine; and   b) one or more poly(hydroxycarboxylic acid) amide salt derivatives having formula (III):       

       [Y—CO[O-A-CO] n -Z r -R + ] m pX q−   (III)         wherein Y is hydrogen or an optionally substituted hydrocarbyl group, A is a divalent optionally substituted hydrocarbyl group, n is from 1 to 100, m is from 1 to 4, q is from 1 to 4 and p is an integer such that pq=m, Z is an optionally substituted divalent bridging group which is attached to the carbonyl group through a nitrogen atom, r is 0 or 1, R +  is an ammonium group and X q−  is an anion.

FIELD OF THE INVENTION

The present invention relates to liquid fuel compositions comprising amajor portion of a base fuel suitable for use in an internal combustionengine, in particular liquid fuel compositions comprising a majorportion of a base fuel suitable for use in an internal combustion engineand a hyperdispersant.

BACKGROUND OF THE INVENTION

EP 0164817 A2 discloses a surfactant comprising a carboxylic acid esteror amide carrying a terminal strong acid group selected fromcarboxymethyl, sulphate, sulphonate, phosphate and phosphonate, suitablefor stabilising dispersions of solids in organic liquids and oil/wateremulsions. A preferred species of the surfactant is apoly(hydroxyalkanecarboxylic acid) having the strong acid groupattached, either directly or through a linking group, to a terminalhydroxy or carboxylic acid group. The use of such surfactants in fuelsis not disclosed therein.

EP 0233684 A1 discloses an ester or polyester having (i) a terminalgroup containing at least two aliphatic carbon-carbon double bonds and(ii) an acidic or basic amino group which is suitable for use as adispersant for solids in organic liquids. The use of such surfactants infuels is not disclosed therein.

GB 2197312 A discloses oil soluble dispersant additives, wherein saiddispersant additives are poly (C₅-C₉ lactone) adducts which have beenprepared by first reacting a C₅-C₉ lactone with a polyamine, a polyol oran amino alcohol to form an intermediate adduct, whereafter theintermediate adduct is reacted with an aliphatic hydrocarbylmonocarboxylic or dicarboxylic acylating agent having from about 1 toabout 165 total carbon atoms. The use of the dispersant additives inlubricating oils and fuels is also disclosed in GB 2197312 A.

EP 0802255 A2 discloses hydroxyl group containing acylated nitrogencompounds which are useful as low chlorine containing additives forlubricating oils and normally liquid fuels and a process for preparingthe compounds.

WO 00/34418 A1 discloses the use of poly(hydroxycarboxylic acid)amide or-ester derivatives in fuel compositions as a lubricity additive. It isalso disclosed in WO 00/34418 A1 that the use of thepoly(hydroxycarboxylic acid)amide or -ester derivatives disclosedtherein may also result in attaining one or more of a number of effectssuch as inlet system cleanliness (intake valves, fuel injectors,carburetors), combustion chamber cleanliness (in each case either orboth of keep clean and clean-up effects), anti-corrosion (includinganti-rust) and reduction or elimination of valve-stick.

SUMMARY OF THE INVENTION

The present invention provides a liquid fuel composition comprising:

-   -   a) a liquid base fuel suitable for use in an internal combustion        engine; and    -   b) one or more poly(hydroxycarboxylic acid) amide salt        derivatives having formula (III):

[Y—CO[O-A-CO]_(n)-Z_(r)-R⁺]_(m)pX^(q−)  (III)

wherein Y is hydrogen or an optionally substituted hydrocarbyl group, Ais a divalent optionally substituted hydrocarbyl group, n is from 1 to100, m is from 1 to 4, q is from 1 to 4 and p is an integer such thatpq=m, Z is an optionally substituted divalent bridging group which isattached to the carbonyl group through a nitrogen atom, r is 0 or 1, R⁺is an ammonium group and X^(q−) is an anion.

The present invention further provides a method for preparing a liquidfuel composition of the present invention comprising admixing the one ormore poly(hydroxycarboxylic acid) amide salt derivatives with a basefuel suitable for use in an internal combustion engine.

The present invention yet further provides a method of operating aninternal combustion engine, which method involves introducing into acombustion chamber of the engine a liquid fuel composition according tothe present invention

It has now been found that the use of poly(hydroxycarboxylic acid) amidesalt derivatives can also surprisingly provides benefits in terms ofimproving the lubricity of liquid fuel compositions incorporated them.

DETAILED DESCRIPTION OF THE INVENTION

The liquid fuel composition of the present invention comprises a basefuel suitable for use in an internal combustion engine and one or morepoly(hydroxycarboxylic acid) amide salt derivatives. Typically, the basefuel suitable for use in an internal combustion engine is a gasoline ora diesel fuel, and therefore the liquid fuel composition of the presentinvention is typically a gasoline composition or a diesel fuelcomposition.

The poly(hydroxycarboxylic acid) amide salt derivatives used in thepresent invention may also be referred to as hyperdispersants.

The one or more poly(hydroxycarboxylic acid) amide salt derivatives inthe liquid fuel compositions of the present invention arepoly(hydroxycarboxylic acid) amide salt derivatives having formula(III):

[Y—CO[O-A-CO]_(n)-Z_(r)-R⁺]_(m)pX^(q−)  (III)

wherein Y is hydrogen or optionally substituted hydrocarbyl group, A isa divalent optionally substituted hydrocarbyl group, n is from 1 to 100,m is from 1 to 4, q is from 1 to 4 and p is an integer such that pq=m, Zis an optionally substituted divalent bridging group which is attachedto the carbonyl group through a nitrogen atom, r is 0 or 1, R⁺ is anammonium group and X^(q−) is an anion.

R⁺ may be a primary, secondary, tertiary or quaternary ammonium group.R⁺ is preferably a quaternary ammonium group.

In formula (III), A is preferably a divalent straight chain or branchedhydrocarbyl group as hereafter described for formulae (I) and (II)below.

That is to say, in formula (III), A is preferably an optionallysubstituted aromatic, aliphatic or cycloaliphatic straight chain orbranched divalent hydrocarbyl group. More preferably, A is an arylene,alkylene or alkenylene group, in particular an arylene, alkylene oralkenylene group containing in the range of from 4 to 25 carbon atoms,more preferably in the range of from 6 to 25 carbon atoms, morepreferably in the range of from 8 to 24 carbon atoms, more preferably inthe range of from 10 to 22 carbon atoms, and most preferably in therange of from 12 to 20 carbon atoms.

Preferably, in said compound of formula (III), there are at least 4carbon atoms, more preferably at least 6 carbon atoms, and even morepreferably in the range of from 8 to 14 carbon atoms connected directlybetween the carbonyl group and the oxygen atom derived from the hydroxylgroup.

In the compound of formula (III), the optional substituents in the groupA are preferably selected from hydroxy, halo or alkoxy groups,especially C₁₋₄ alkoxy groups.

In formula (III) (and formula (I)), n is in the range of from 1 to 100.Preferably, the lower limit of the range for n is 1, more preferably 2,even more preferably 3; preferably the upper limit of the range for n is100, more preferably 60, more preferably 40, more preferably 20, andeven more preferably 10 (i.e. n may be selected from any of thefollowing ranges: from 1 to 100; from 2 to 100; from 3 to 100; from 1 to60; from 2 to 60; from 3 to 60; from 1 to 40; from 2 to 40; from 3 to40; from 1 to 20; from 2 to 20; from 3 to 20; from 1 to 10; from 2 to10; and, from 3 to 10).

In formula (III), Y is preferably an optionally substituted hydrocarbylgroup as hereinafter described for formula (I).

That is to say, the optionally substituted hydrocarbyl group Y informula (III) is preferably aryl, alkyl or alkenyl containing up to 50carbon atoms, more preferably in the range of from 7 to 25 carbon atoms.For example, the optionally substituted hydrocarbyl group Y may beconveniently selected from heptyl, octyl, undecyl, lauryl, heptadecyl,heptadenyl, heptadecadienyl, stearyl, oleyl and linoleyl.

Other examples of said optionally substituted hydrocarbyl group Y informula (III) herein include C₄₋₈ cycloalkyls such as cyclohexyl;polycycloalkyls such as polycyclic terpenyl groups which are derivedfrom naturally occurring acids such as abietic acid; aryls such asphenyl; aralkyls such as benzyl; and polyaryls such as naphthyl,biphenyl, stibenzyl and phenylmethylphenyl.

In the present invention, the optionally substituted hydrocarbyl group Yin formula (III) may contain one or more functional groups such ascarbonyl, carboxyl, nitro, hydroxy, halo, alkoxy, amino, preferablytertiary amino (no N—H linkages), oxy, cyano, sulphonyl and sulphoxyl.The majority of the atoms, other than hydrogen, in substitutedhydrocarbyl groups are generally carbon, with the heteroatoms (e.g.,oxygen, nitrogen and sulphur) generally representing only a minority,about 33% or less, of the total non-hydrogen atoms present.

Those skilled in the art will appreciate that functional groups such ashydroxy, halo, alkoxy, nitro and cyano in a substituted hydrocarbylgroup Y will displace one of the hydrogen atoms of the hydrocarbyl,whilst functional groups such as carbonyl, carboxyl, tertiary amino(—N—), oxy, sulphonyl and sulphoxyl in a substituted hydrocarbyl groupwill displace a —CH— or —CH₂— moiety of the hydrocarbyl.

More preferably, the hydrocarbyl group Y in formula (III) isunsubstituted or substituted by a group selected from hydroxy, halo oralkoxy group, even more preferably C₁₋₄ alkoxy.

Most preferably, the optionally substituted hydrocarbyl group Y informula (III) is a stearyl group, 12-hydroxystearyl group, an oleylgroup or a 12-hydroxyoleyl group, and that derived from naturallyoccurring oil such as tall oil fatty acid.

In formula (III), Z is preferably an optionally substituted divalentbridging group represented by formula (IV)

wherein R¹ is hydrogen or a hydrocarbyl group and B is an optionallysubstituted alkylene group.

Examples of hydrocarbyl groups that may represent R¹ include methyl,ethyl, n-propyl, n-butyl and octadecyl.

Examples of optionally substituted alkylene groups that may represent Binclude ethylene, trimethylene, tetramethylene and hexamethylene.

Examples of preferred Z moieties in formula (III) include —NHCH₂CH₂—,—NHCH₂C(CH₃)₂CH₂— and —NH(CH₂)₃—.

In formula (III), r is preferably 1, i.e. the poly(hydroxycarboxylicacid) amide salt derivative having formula (III) must contain theoptionally substituted divalent bridging group Z.

Preferably, R⁺ may be represented by formula (V)

wherein R², R³ and R⁴ may be selected from hydrogen and alkyl groupssuch as methyl.

The anion X^(q−) of the compound of formula (III) is not critical andcan be any anion (or mixture of anions) suitable to balance the positivecharge of the poly(hydroxycarboxylic acid) amide cation.

The anion X^(q−) of the compound of formula (III) may conveniently be asulphur-containing anion, such as an anion selected from sulphate andsulphonate anions.

However, since it is desirable to maintain a low sulphur content ingasoline and diesel fuels, the use of non-sulphur-containing anions inthe compounds of formula (III) may be desirable depending upon theconcentration of sulphur in the liquid base fuel and/or the desiredconcentration of sulphur in the liquid fuel composition containing theone or more poly(hydroxycarboxylic acid) amide salt derivatives.

Therefore, the anion X^(q−) of the compound of formula (III) can also beany non-sulphur-containing anion (or mixture of anions) suitable tobalance the positive charge of the poly(hydroxycarboxylic acid) amidecation, such as a non-sulphur-containing organic anion or anon-sulphur-containing inorganic anion.

Non-limiting examples of suitable anions are OH⁻, CH⁻, NH₃ ⁻, HCO₃ ⁻,HCOO⁻, CH₃COO⁻, H⁻, BO₃ ³⁻, cO₃ ²⁻, C₂H₃O₂ ⁻, HCO²⁻, C₂O₄ ²⁻, HC₂O₄ ⁻,NO₂ ⁻, NO₂ ⁻, N³⁻, NH₂ ⁻, O²⁻, O₂ ²⁻, BeF₃ ⁻, F⁻, Na⁻, [Al(H₂O)₂(OH)₄]⁻,SiO₃ ⁻, SiF₆ ⁻, H₂PO₄ ⁻, P³⁻, PO₄ ³⁻, HPO₄ ²⁻, Cl⁻, ClO₃ ⁻, ClO₄ ⁻,ClO⁻, KO⁻, SbOH₆ ⁻, SnCl₆ ²⁻, [SnTe4]⁴⁻, CrO₄ ²⁻, Cr₂O₇ ²⁻, MnO₄ ⁻,NiCl₆ ²⁻, [Cu(CO₃)₂(OH)₂]⁴⁻, AsO₄ ³⁻, Br⁻, BrO₃ ⁻, IO₃ ⁻, I⁻, CN⁻, OCN⁻,etc.

Suitable anions may also include anions derived from compoundscontaining a carboxylic acid group (e.g. a carboxylate anion), anionsderived from compounds containing a hydroxyl group (e.g. an alkoxide,phenoxide or enolate anion), nitrogen based anions such as nitrate andnitrite, phosphorus based anions such as phosphates and phosphonates, ormixtures thereof.

Non-limiting examples of suitable anions derived from compoundscontaining a carboxylic acid group include acetate, oleate, salicylateanions, and mixtures thereof.

Non-limiting examples of suitable anions derived from compoundscontaining a hydroxyl group include phenate anions, and mixturesthereof.

In a preferred embodiment of the present invention, the anion X^(q−) isa non-sulfur-containing anion selected from the group consisting of OH,a phenate group, a salicylate group, an oleate group and an acetategroup; more preferably the anion X^(q−) is OH.

The one or more poly(hydroxycarboxylic acid) amide salt derivatives maybe obtained by reaction of an amine and a poly(hydroxycarboxylic acid)of formula (I)

Y—CO[O-A-CO]_(n)—OH  (I)

wherein Y is hydrogen or optionally substituted hydrocarbyl group, A isa divalent optionally substituted hydrocarbyl group and n is from 1 to100, with an acid or a quaternizing agent.

As used herein, the term “hydrocarbyl” represents a radical formed byremoval of one or more hydrogen atoms from a carbon atom of ahydrocarbon (not necessarily the same carbon atoms in case more hydrogenatoms are removed).

Hydrocarbyl groups may be aromatic, aliphatic, acyclic or cyclic groups.Preferably, hydrocarbyl groups are aryl, cycloalkyl, alkyl or alkenyl,in which case they may be straight-chain or branched-chain groups.

Representative hydrocarbyl groups include phenyl, naphthyl, methyl,ethyl, butyl, pentyl, methylpentyl, hexenyl, dimethylhexyl, octenyl,cyclooctenyl, methylcyclooctenyl, dimethylcyclooctyl, ethylhexyl, octyl,isooctyl, dodecyl, hexadecenyl, eicosyl, hexacosyl, triacontyl andphenylethyl.

In the present invention, the phrase “optionally substitutedhydrocarbyl” is used to describe hydrocarbyl groups optionallycontaining one or more “inert” heteroatom-containing functional groups.By “inert” is meant that the functional groups do not interfere to anysubstantial degree with the function of the compound.

The optionally substituted hydrocarbyl group Y in formula (I) herein ispreferably aryl, alkyl or alkenyl containing up to 50 carbon atoms, morepreferably in the range of from 7 to 25 carbon atoms. For example, theoptionally substituted hydrocarbyl group Y may be conveniently selectedfrom heptyl, octyl, undecyl, lauryl, heptadecyl, heptadenyl,heptadecadienyl, stearyl, oleyl and linoleyl.

Other examples of said optionally substituted hydrocarbyl group Y informula (I) herein include C₄₋₈ cycloalkyls such as cyclohexyl;polycycloalkyls such as polycyclic terpenyl groups which are derivedfrom naturally occurring acids such as abietic acid; aryls such asphenyl; aralkyls such as benzyl; and polyaryls such as naphthyl,biphenyl, stibenzyl and phenylmethylphenyl.

In the present invention, the optionally substituted hydrocarbyl group Ymay contain one or more functional groups such as carbonyl, carboxyl,nitro, hydroxy, halo, alkoxy, tertiary amino (no N—H linkages), oxy,cyano, sulphonyl and sulphoxyl. The majority of the atoms, other thanhydrogen, in substituted hydrocarbyl groups are generally carbon, withthe heteroatoms (e.g., oxygen, nitrogen and sulphur) generallyrepresenting only a minority, about 33% or less, of the totalnon-hydrogen atoms present.

Those skilled in the art will appreciate that functional groups such ashydroxy, halo, alkoxy, nitro and cyano in a substituted hydrocarbylgroup Y will displace one of the hydrogen atoms of the hydrocarbyl,whilst functional groups such as carbonyl, carboxyl, tertiary amino(—N—), oxy, sulphonyl and sulphoxyl in a substituted hydrocarbyl groupwill displace a —CH— or —CH₂— moiety of the hydrocarbyl.

The hydrocarbyl group Y in formula (I) is more preferably unsubstitutedor substituted by a group selected from hydroxy, halo or alkoxy group,even more preferably C₁₋₄ alkoxy.

Most preferably, the optionally substituted hydrocarbyl group Y informula (I) is a stearyl group, 12-hydroxystearyl group, an oleyl group,a 12-hydroxyoleyl group or a group derived from naturally occurring oilsuch as tall oil fatty acid.

In one embodiment of the present invention, at least one of, or all of,the one or more poly(hydroxycarboxylic acid) amide salt derivatives aresulphur-containing poly(hydroxycarboxylic acid) amide salt derivatives.

In such an embodiment, said one or more poly(hydroxycarboxylic acid)amide salt derivatives preferably have a sulphur content of at most 2.5wt. %, such as a sulphur content in the range of from 0.1 to 2.0 wt. %,conveniently in the range of from 0.6 to 1.2 wt. % sulphur, as measuredby ICP-AES, based on the total weight of said poly(hydroxycarboxylicacid) amide salt derivatives.

In another embodiment of the present invention, the one or morepoly(hydroxycarboxylic acid) amide salt derivatives arenon-sulphur-containing poly(hydroxycarboxylic acid) amide saltderivatives.

The preparation of poly(hydroxycarboxylic acid) and its amide or otherderivatives is known and is described, for instance, in EP 0 164 817, WO95/17473, WO 96/07689, U.S. Pat. No. 5,536,445, GB 2 001 083, GB 1 342746, GB 1 373 660, U.S. Pat. No. 5,000,792 and U.S. Pat. No. 4,349,389which disclosures are herein incorporated by reference.

The poly(hydroxycarboxylic acid)s of formula (I) may be made by theinteresterification of one or more hydroxycarboxylic acids of formula(II)

HO-A-COOH  (II)

wherein A is a divalent optionally substituted hydrocarbyl group,optionally in the presence of a catalyst according to well knownmethods. Such methods are described, for example, in U.S. Pat. No.3,996,059, GB 1 373 660 and GB 1 342 746.

The chain terminator in said interesterification may be anon-hydroxycarboxylic acid.

The hydroxyl group in the hydroxycarboxylic acid and the carboxylic acidgroup in the hydroxycarboxylic acid or the non-hydroxycarboxylic acidmay be primary, secondary or tertiary in character.

The interesterification of the hydroxycarboxylic acid and thenon-hydroxycarboxylic acid chain terminator may be effected by heatingthe starting materials, optionally in a suitable hydrocarbon solventsuch as toluene or xylene, and azeotroping off the formed water. Thereaction may be carried out at a temperature up to −250° C.,conveniently at the reflux temperature of the solvent.

Where the hydroxyl group in the hydroxycarboxylic acid is secondary ortertiary, the temperature employed should not be so high as to lead todehydration of the acid molecule.

Catalysts for the interesterification, such as p-toluenesulphonic acid,zinc acetate, zirconium naphthenate or tetrabutyl titanate, may beincluded, with the objective of either increasing the rate of reactionat a given temperature or of reducing the temperature required for agiven rate of reaction.

In the compounds of formulae (I) and (II), A is preferably an optionallysubstituted aromatic, aliphatic or cycloaliphatic straight chain orbranched divalent hydrocarbyl group. Preferably, A is an arylene,alkylene or alkenylene group, in particular an arylene, alkylene oralkenylene group containing in the range of from 4 to 25 carbon atoms,more preferably in the range of from 6 to 25 carbon atoms, morepreferably in the range of from 8 to 24 carbon atoms, more preferably inthe range of from 10 to 22 carbon atoms, and most preferably in therange of from 12 to 20 carbon atoms.

Preferably, in said compounds of formulae (I) and (II), there are atleast 4 carbon atoms, more preferably at least 6 carbon atoms, and evenmore preferably in the range of from 8 to 14 carbon atoms connecteddirectly between the carbonyl group and the oxygen atom derived from thehydroxyl group.

In the compounds of formulae (I) and (II), the optional substituents inthe group A are preferably selected from hydroxy, halo or alkoxy groups,more preferably C₁₋₄ alkoxy groups.

The hydroxyl group in the hydroxycarboxylic acids of formula (II) ispreferably a secondary hydroxyl group.

Examples of suitable hydroxycarboxylic acids are 9-hydroxystearic acid,10-hydroxystearic acid, 12-hydroxystearic acid, 12-hydroxy-9-oleic acid(ricinoleic acid), 6-hydroxycaproic acid, preferably 12-hydroxystearicacid. Commercial 12-hydroxystearic acid (hydrogenated castor oil fattyacid) normally contains up to 15% wt of stearic acid and othernon-hydroxycarboxylic acids as impurities and can conveniently be usedwithout further admixture to produce a polymer of molecular weight about1000-2000.

Where the non-hydroxycarboxylic acid is introduced separately to thereaction, the proportion which is required in order to produce a polymeror oligomer of a given molecular weight can be determined either bysimple experiment or by calculation by the person skilled in the art.

The group (—O-A-CO—) in the compounds of formulae (I) and (II) ispreferably a 12-oxystearyl group, 12-oxyoleyl group or a 6-oxycaproylgroup.

Preferred poly(hydroxycarboxylic acid)s of formula (I) for reaction withamine include poly(hydroxystearic acid) and poly(hydroxyoleic acid).

The amines which react with poly(hydroxycarboxylic acid)s of formula (I)to form poly(hydroxycarboxylic acid) amide intermediates may includethose defined in WO 97/41092.

For example, various amines and their preparations are described in U.S.Pat. No. 3,275,554, U.S. Pat. No. 3,438,757, U.S. Pat. No. 3,454,555,U.S. Pat. No. 3,565,804, U.S. Pat. No. 3,755,433 and U.S. Pat. No.3,822,209 which disclosures are herein incorporated by reference.

The amine reactant is preferably a diamine, a triamine or a polyamine.

Preferred amine reactants are diamines selected from ethylenediamine,N,N-dimethyl-1,3-propanediamine, triamines and polyamines selected fromdietheylenetriamine, triethylenetetramine, tetraethylenepentamine,pentaethylenehexamine and tris(2-aminoethyl)amine.

The amidation between the amine reactant and the (poly(hydroxycarboxylicacid) of formula (I) may be carried out according to methods known tothose skilled in the art, by heating the poly(hydroxycarboxylic acid)with the amine reactant, optionally in a suitable hydrocarbon solventsuch as toluene or xylene, and azeotroping off the formed water. Saidreaction may be carried out in the presence of a catalyst such asp-toluenesulphonic acid, zinc acetate, zirconium naphthenate ortetrabutyl titanate.

Various patent documents disclose poly(hydroxycarboxylic acid) amidederivatives.

For instance, GB 1 373 660 discloses poly(hydroxycarboxylic acid) amidederivatives with amines such as 3-dimethylaminopropylamine andethylenediamine for use as dispersing agents in dispersions of pigmentsin organic liquids.

GB 2 001 083 discloses poly(hydroxycarboxylic acid) amide derivativeswith poly(ethyleneimine) (PEI) having a molecular weight (MW) greaterthan 500 for a similar use.

In U.S. Pat. No. 5,000,792, poly(hydroxycarboxylic acid) amidederivatives with amines of the formula of NH²⁻R′—N(R″)—R′″—NH₂ aredisclosed for use as pigment dispersing agent.

WO 95/17473 discloses poly(hydroxycarboxylic acid) amide derivativeswith amines such as 3-dimethylaminopropylamine, ethylenediamine,poly(ethyleneimine) (PEI) having a molecular weight (MW) greater than500 and amines of the formula of NH₂R′—N(R″)—R′″—NH₂ for use in a methodof preparing a non-aqueous dispersion of copper phthalocyanine.

U.S. Pat. No. 4,349,389 discloses poly(hydroxycarboxylic acid) amidederivatives with amines such as 3-dimethyl-aminopropylamine,poly(ethyleneimine) (PEI) having a molecular weight (MW) greater than500 as dispersing agent in the preparation of a dispersible inorganicpigment composition.

EP 0 164 817 discloses poly(hydroxycarboxylic acid) amide derivativeswith polyamines (ethylenediamine, diethylenetriamine, etc.),aminoalcohols (diethanolamine, etc.) and ester derivatives with polyols(glycerol, etc.) for use as surfactant suitable for stabilisingdispersions of solids in organic liquids and oil/water emulsions.

However, none of the afore-mentioned patent documents disclose the useof one or more poly(hydroxycarboxylic acid) amide salt derivatives asdisclosed herein in fuel compositions.

The poly(hydroxycarboxylic acid) amide intermediate formed from reactionof the amine and the poly(hydroxycarboxylic acid) of formula (I) isreacted with an acid or a quaternizing agent to form a salt derivative,according to well-known methods.

Acids that may be used to form the salt derivative may be selected fromorganic or inorganic acids. Said acids are conveniently selected fromcarboxylic acids, nitrogen-containing organic and inorganic acids,sulphur-containing organic or inorganic acids (such as sulphuric acid,methanesulphonic acid and benzenesulphonic acid).

Quaternizing agents that may be used to form the salt derivative may beselected from dimethylsulphuric acid, a dialkyl sulphate having from 1to 4 carbon atoms, an alkyl halide such as methyl chloride, methylbromide, aryl halide such as benzyl chloride.

In a preferred embodiment, the quaternizing agent is asulphur-containing quaternizing agent, in particular dimethylsulphuricacid or an dialkyl sulphate having from 1 to 4 carbon atoms. Thequaternizing agent is preferably dimethyl sulphate.

Quaternization is a well-known method in the art. For example,quaternization using dimethyl sulphate is described in U.S. Pat. No.3,996,059, U.S. Pat. No. 4,349,389 and GB 1 373 660.

Poly(hydroxycarboxylic acid) amide salt derivatives that are preferredin the present invention are those which each have a TBN (total basenumber) value of less than 10 mg·KOH/g, as measured by ASTM D 4739. Morepreferably, the poly(hydroxycarboxylic acid) amide salt derivatives eachhave a TBN value of less than 5 mg·KOH/g, most preferably 2 mg·KOH/g orless, as measured by ASTM D 4739.

Examples of poly(hydroxycarboxylic acid) amide salt derivatives that areavailable commercially include that available from Lubrizol under thetrade designation “SOLSPERSE 17000” (a reaction product ofpoly(12-hydroxystearic acid) with N,N-dimethyl-1,3-propanediamine anddimethyl sulphate) and those available under the trade designations“CH-5” and “CH-7” from Shanghai Sanzheng Polymer Company.

In the liquid fuel compositions of the present invention, if the basefuel used is a gasoline, then the gasoline may be any gasoline suitablefor use in an internal combustion engine of the spark-ignition (petrol)type known in the art. The gasoline used as the base fuel in the liquidfuel composition of the present invention may conveniently also bereferred to as ‘base gasoline’.

Gasolines typically comprise mixtures of hydrocarbons boiling in therange from 25 to 230° C. (EN-ISO 3405), the optimal ranges anddistillation curves typically varying according to climate and season ofthe year. The hydrocarbons in a gasoline may be derived by any meansknown in the art, conveniently the hydrocarbons may be derived in anyknown manner from straight-run gasoline, synthetically-produced aromatichydrocarbon mixtures, thermally or catalytically cracked hydrocarbons,hydro-cracked petroleum fractions, catalytically reformed hydrocarbonsor mixtures of these.

The specific distillation curve, hydrocarbon composition, researchoctane number (RON) and motor octane number (MON) of the gasoline arenot critical.

Conveniently, the research octane number (RON) of the gasoline may be atleast 80, for instance in the range of from 80 to 110, preferably theRON of the gasoline will be at least 90, for instance in the range offrom 90 to 110, more preferably the RON of the gasoline will be at least91, for instance in the range of from 91 to 105, even more preferablythe RON of the gasoline will be at least 92, for instance in the rangeof from 92 to 103, even more preferably the RON of the gasoline will beat least 93, for instance in the range of from 93 to 102, and mostpreferably the RON of the gasoline will be at least 94, for instance inthe range of from 94 to 100 (EN 25164); the motor octane number (MON) ofthe gasoline may conveniently be at least 70, for instance in the rangeof from 70 to 110, preferably the MON of the gasoline will be at least75, for instance in the range of from 75 to 105, more preferably the MONof the gasoline will be at least 80, for instance in the range of from80 to 100, most preferably the MON of the gasoline will be at least 82,for instance in the range of from 82 to 95 (EN 25163).

Typically, gasolines comprise components selected from one or more ofthe following groups; saturated hydrocarbons, olefinic hydrocarbons,aromatic hydrocarbons, and oxygenated hydrocarbons. Conveniently, thegasoline may comprise a mixture of saturated hydrocarbons, olefinichydrocarbons, aromatic hydrocarbons, and, optionally, oxygenatedhydrocarbons.

Typically, the olefinic hydrocarbon content of the gasoline is in therange of from 0 to 40 percent by volume based on the gasoline (ASTMD1319); preferably, the olefinic hydrocarbon content of the gasoline isin the range of from 0 to 30 percent by volume based on the gasoline,more preferably, the olefinic hydrocarbon content of the gasoline is inthe range of from 0 to 20 percent by volume based on the gasoline.

Typically, the aromatic hydrocarbon content of the gasoline is in therange of from 0 to 70 percent by volume based on the gasoline (ASTMD1319), for instance the aromatic hydrocarbon content of the gasoline isin the range of from 10 to 60 percent by volume based on the gasoline;preferably, the aromatic hydrocarbon content of the gasoline is in therange of from 0 to 50 percent by volume based on the gasoline, forinstance the aromatic hydrocarbon content of the gasoline is in therange of from 10 to 50 percent by volume based on the gasoline.

The benzene content of the gasoline is at most 10 percent by volume,more preferably at most 5 percent by volume, especially at most 1percent by volume based on the gasoline.

The gasoline preferably has a low or ultra low sulphur content, forinstance at most 1000 ppmw (parts per million by weight), preferably nomore than 500 ppmw, more preferably no more than 100, even morepreferably no more than 50 and most preferably no more than even 10ppmw.

The gasoline also preferably has a low total lead content, such as atmost 0.005 g/l, most preferably being lead free—having no lead compoundsadded thereto (i.e. unleaded).

When the gasoline comprises oxygenated hydrocarbons, at least a portionof non-oxygenated hydrocarbons will be substituted for oxygenatedhydrocarbons. The oxygen content of the gasoline may be up to 35 percentby weight (EN 1601) (e.g. ethanol per se) based on the gasoline. Forexample, the oxygen content of the gasoline may be up to 25 percent byweight, preferably up to 10 percent by weight. Conveniently, theoxygenate concentration will have a minimum concentration selected fromany one of 0, 0.2, 0.4, 0.6, 0.8, 1.0, and 1.2 percent by weight, and amaximum concentration selected from any one of 5, 4.5, 4.0, 3.5, 3.0,and 2.7 percent by weight.

Examples of oxygenated hydrocarbons that may be incorporated into thegasoline include alcohols, ethers, esters, ketones, aldehydes,carboxylic acids and their derivatives, and oxygen containingheterocyclic compounds. Preferably, the oxygenated hydrocarbons that maybe incorporated into the gasoline are selected from alcohols (such asmethanol, ethanol, propanol, iso-propanol, butanol, tert-butanol andiso-butanol), ethers (preferably ethers containing 5 or more carbonatoms per molecule, e.g., methyl tert-butyl ether) and esters(preferably esters containing 5 or more carbon atoms per molecule); aparticularly preferred oxygenated hydrocarbon is ethanol.

When oxygenated hydrocarbons are present in the gasoline, the amount ofoxygenated hydrocarbons in the gasoline may vary over a wide range. Forexample, gasolines comprising a major proportion of oxygenatedhydrocarbons are currently commercially available in countries such asBrazil and U.S.A, e.g. ethanol per se and E85, as well as gasolinescomprising a minor proportion of oxygenated hydrocarbons, e.g. E10 andE5. Therefore, the gasoline may contain up to 100 percent by volumeoxygenated hydrocarbons. Preferably, the amount of oxygenatedhydrocarbons present in the gasoline is selected from one of thefollowing amounts: up to 85 percent by volume; up to 65 percent byvolume; up to 30 percent by volume; up to 20 percent by volume; up to 15percent by volume; and, up to 10 percent by volume, depending upon thedesired final formulation of the gasoline. Conveniently, the gasolinemay contain at least 0.5, 1.0 or 2.0 percent by volume oxygenatedhydrocarbons.

Examples of suitable gasolines include gasolines which have an olefinichydrocarbon content of from 0 to 20 percent by volume (ASTM D1319), anoxygen content of from 0 to 5 percent by weight (EN 1601), an aromatichydrocarbon content of from 0 to 50 percent by volume (ASTM D1319) and abenzene content of at most 1 percent by volume.

Whilst not critical to the present invention, the base gasoline or thegasoline composition of the present invention may convenientlyadditionally include one or more fuel additive. The concentration andnature of the fuel additive(s) that may be included in the base gasolineor the gasoline composition of the present invention is not critical.Non-limiting examples of suitable types of fuel additives that can beincluded in the base gasoline or the gasoline composition of the presentinvention include anti-oxidants, corrosion inhibitors, detergents,dehazers, antiknock additives, metal deactivators, valve-seat recessionprotectant compounds, dyes, friction modifiers, carrier fluids, diluentsand markers. Examples of suitable such additives are described generallyin U.S. Pat. No. 5,855,629.

Conveniently, the fuel additives can be blended with one or morediluents or carrier fluids, to form an additive concentrate, theadditive concentrate can then be admixed with the base gasoline or thegasoline composition of the present invention.

The (active matter) concentration of any additives present in the basegasoline or the gasoline composition of the present invention ispreferably up to 1 percent by weight, more preferably in the range from5 to 1000 ppmw, advantageously in the range of from 75 to 300 ppmw, suchas from 95 to 150 ppmw.

In the liquid fuel compositions of the present invention, if the basefuel used is a diesel fuel, then the diesel fuel used as the base fuelin the present invention includes diesel fuels for use in automotivecompression ignition engines, as well as in other types of engine suchas for example marine, railroad and stationary engines. The diesel fuelused as the base fuel in the liquid fuel composition of the presentinvention may conveniently also be referred to as ‘diesel base fuel’.

The diesel base fuel may itself comprise a mixture of two or moredifferent diesel fuel components, and/or be additivated as describedbelow.

Such diesel fuels will contain one or more base fuels which maytypically comprise liquid hydrocarbon middle distillate gas oil(s), forinstance petroleum derived gas oils. Such fuels will typically haveboiling points within the usual diesel range of 150 to 400° C.,depending on grade and use. They will typically have a density from 750to 1000 kg/m³, preferably from 780 to 860 kg/m³, at 15° C. (e.g. ASTMD4502 or IP 365) and a cetane number (ASTM D613) of from 35 to 120, morepreferably from 40 to 85. They will typically have an initial boilingpoint in the range 150 to 230° C. and a final boiling point in the range290 to 400° C. Their kinematic viscosity at 40° C. (ASTM D445) mightsuitably be from 1.2 to 4.5 mm²/s.

An example of a petroleum derived gas oil is a Swedish Class 1 basefuel, which will have a density from 800 to 820 kg/m³ at 15° C. (SS-ENISO 3675, SS-EN ISO 12185), a T95 of 320° C. or less (SS-EN ISO 3405)and a kinematic viscosity at 40° C. (SS-EN ISO 3104) from 1.4 to 4.0mm²/s, as defined by the Swedish national specification EC1.

Optionally, non-mineral oil based fuels, such as biofuels orFischer-Tropsch derived fuels, may also form or be present in the dieselfuel. Such Fischer-Tropsch fuels may for example be derived from naturalgas, natural gas liquids, petroleum or shale oil, petroleum or shale oilprocessing residues, coal or biomass.

The amount of Fischer-Tropsch derived fuel used in the diesel fuel maybe from 0% to 100% v of the overall diesel fuel, preferably from 5% to100% v, more preferably from 5% to 75% v. It may be desirable for such adiesel fuel to contain 10% v or greater, more preferably 20% v orgreater, still more preferably 30% v or greater, of the Fischer-Tropschderived fuel. It is particularly preferred for such diesel fuels tocontain 30 to 75% v, and particularly 30 or 70% v, of theFischer-Tropsch derived fuel. The balance of the diesel fuel is made upof one or more other diesel fuel components.

Such a Fischer-Tropsch derived fuel component is any fraction of themiddle distillate fuel range, which can be isolated from the (optionallyhydrocracked) Fischer-Tropsch synthesis product. Typical fractions willboil in the naphtha, kerosene or gas oil range. Preferably, aFischer-Tropsch product boiling in the kerosene or gas oil range is usedbecause these products are easier to handle in for example domesticenvironments. Such products will suitably comprise a fraction largerthan 90 wt % which boils between 160 and 400° C., preferably to about370° C. Examples of Fischer-Tropsch derived kerosene and gas oils aredescribed in EP-A-0583836, WO-A-97/14768, WO-A-97/14769, WO-A-00/11116,WO-A-00/11117, WO-A-01/83406, WO-A-01/83648, WO-A-01/83647,WO-A-01/83641, WO-A-00/20535, WO-A-00/20534, EP-A-1101813, U.S. Pat. No.5,766,274, U.S. Pat. No. 5,378,348, U.S. Pat. No. 5,888,376 and U.S.Pat. No. 6,204,426 which disclosures are herein incorporated byreference.

The Fischer-Tropsch product will suitably contain more than about 80 wt% and more suitably more than about 95 wt % iso and normal paraffins andless than about 1 wt % aromatics, the balance being naphthenicscompounds. The content of sulphur and nitrogen will be very low andnormally below the detection limits for such compounds. For this reasonthe sulphur content of a diesel fuel composition containing aFischer-Tropsch product may be very low.

The diesel fuel composition preferably contains no more than 5000 ppmwsulphur, more preferably no more than 500 ppmw, or no more than 350ppmw, or no more than 150 ppmw, or no more than 100 ppmw, or no morethan 70 ppmw, or no more than 50 ppmw, or no more than 30 ppmw, or nomore than 20 ppmw, or most preferably no more than 15 ppmw sulphur.

The diesel base fuel may itself be additivated (additive-containing) orunadditivated (additive-free). If additivated, e.g. at the refinery, itwill contain minor amounts of one or more additives selected for examplefrom anti-static agents, pipeline drag reducers, flow improvers (e.g.ethylene/vinyl acetate copolymers or acrylate/maleic anhydridecopolymers), lubricity additives, antioxidants and wax anti-settlingagents.

Detergent-containing diesel fuel additives are known and commerciallyavailable. Such additives may be added to diesel fuels at levelsintended to reduce, remove, or slow the build up of engine deposits.

Examples of detergents suitable for use in diesel fuel additives for thepresent purpose include polyolefin substituted succinimides orsuccinamides of polyamines, for instance polyisobutylene succinimides orpolyisobutylene amine succinamides, aliphatic amines, Mannich bases oramines and polyolefin (e.g. polyisobutylene) maleic anhydrides.Succinimide dispersant additives are described for example inGB-A-960493, EP-A-0147240, EP-A-0482253, EP-A-0613938, EP-A-0557516 andWO-A-98/42808. Particularly preferred are polyolefin substitutedsuccinimides such as polyisobutylene succinimides.

The diesel fuel additive mixture may contain other components inaddition to the detergent. Examples are lubricity enhancers; dehazers,e.g. alkoxylated phenol formaldehyde polymers; anti-foaming agents (e.g.polyether-modified polysiloxanes); ignition improvers (cetane improvers)(e.g. 2-ethylhexyl nitrate (EHN), cyclohexyl nitrate, di-tert-butylperoxide and those disclosed in U.S. Pat. No. 4,208,190 at column 2,line 27 to column 3, line 21) which disclosure is herein incorporated byreference; anti-rust agents (e.g. a propane-1,2-diol semi-ester oftetrapropenyl succinic acid, or polyhydric alcohol esters of a succinicacid derivative, the succinic acid derivative having on at least one ofits alpha-carbon atoms an unsubstituted or substituted aliphatichydrocarbon group containing from 20 to 500 carbon atoms, e.g. thepentaerythritol diester of polyisobutylene-substituted succinic acid);corrosion inhibitors; reodorants; anti-wear additives; anti-oxidants(e.g. phenolics such as 2,6-di-tert-butylphenol, or phenylenediaminessuch as N,N′-di-sec-butyl-p-phenylenediamine); metal deactivators;combustion improvers; static dissipator additives; cold flow improvers;and wax anti-settling agents.

The diesel fuel additive mixture may contain a lubricity enhancer,especially when the diesel fuel composition has a low (e.g. 500 ppmw orless) sulphur content. In the additivated diesel fuel composition, thelubricity enhancer is conveniently present at a concentration of lessthan 1000 ppmw, preferably between 50 and 1000 ppmw, more preferablybetween 70 and 1000 ppmw. Suitable commercially available lubricityenhancers include ester- and acid-based additives. Other lubricityenhancers are described in the patent literature, in particular inconnection with their use in low sulphur content diesel fuels, forexample in:

-   -   the paper by Danping Wei and H. A. Spikes, “The Lubricity of        Diesel Fuels”, Wear, III (1986) 217-235;    -   WO-A-95/33805—cold flow improvers to enhance lubricity of low        sulphur fuels;    -   WO-A-94/17160—certain esters of a carboxylic acid and an alcohol        wherein the acid has from 2 to 50 carbon atoms and the alcohol        has 1 or more carbon atoms, particularly glycerol monooleate and        di-isodecyl adipate, as fuel additives for wear reduction in a        diesel engine injection system;    -   U.S. Pat. No. 5,490,864—certain dithiophosphoric        diester-dialcohols as anti-wear lubricity additives for low        sulphur diesel fuels; and    -   WO-A-98/01516—certain alkyl aromatic compounds having at least        one carboxyl group attached to their aromatic nuclei, to confer        anti-wear lubricity effects particularly in low sulphur diesel        fuels.

It may also be preferred for the diesel fuel composition to contain ananti-foaming agent, more preferably in combination with an anti-rustagent and/or a corrosion inhibitor and/or a lubricity enhancingadditive.

Unless otherwise stated, the (active matter) concentration of each suchadditive component in the additivated diesel fuel composition ispreferably up to 10000 ppmw, more preferably in the range from 0.1 to1000 ppmw, advantageously from 0.1 to 300 ppmw, such as from 0.1 to 150ppmw.

The (active matter) concentration of any dehazer in the diesel fuelcomposition will preferably be in the range from 0.1 to 20 ppmw, morepreferably from 1 to 15 ppmw, still more preferably from 1 to 10 ppmw,advantageously from 1 to 5 ppmw. The (active matter) concentration ofany ignition improver present will preferably be 2600 ppmw or less, morepreferably 2000 ppmw or less, conveniently from 300 to 1500 ppmw. The(active matter) concentration of any detergent in the diesel fuelcomposition will preferably be in the range from 5 to 1500 ppmw, morepreferably from 10 to 750 ppmw, most preferably from 20 to 500 ppmw.

In the case of a diesel fuel composition, for example, the fuel additivemixture will typically contain a detergent, optionally together withother components as described above, and a diesel fuel-compatiblediluent, which may be a mineral oil, a solvent such as those sold byShell companies under the trade mark “SHELLSOL”, a polar solvent such asan ester and, in particular, an alcohol, e.g. hexanol, 2-ethylhexanol,decanol, isotridecanol and alcohol mixtures such as those sold by Shellcompanies under the trade mark “LINEVOL”, especially LINEVOL 79 alcoholwhich is a mixture of C₇₋₉ primary alcohols, or a C₁₂₋₁₄ alcohol mixturewhich is commercially available.

The total content of the additives in the diesel fuel composition may besuitably between 0 and 10000 ppmw and preferably below 5000 ppmw.

In the above, amounts (concentrations, % vol, ppmw, % wt) of componentsare of active matter, i.e. exclusive of volatile solvents/diluentmaterials.

The liquid fuel composition of the present invention is produced byadmixing the one or more poly(hydroxycarboxylic acid) amide saltderivatives with a base fuel suitable for use in an internal combustionengine. If the base fuel to which the one or more poly(hydroxycarboxylicacid) amide salt derivatives is admixed is a gasoline, then the liquidfuel composition produced is a gasoline composition; likewise, if thebase fuel to which the one or more poly(hydroxycarboxylic acid) amidesalt derivatives is admixed is a diesel fuel, then the liquid fuelcomposition produced is a diesel fuel composition.

Preferably, the amount of the one or more poly(hydroxycarboxylic acid)amide salt derivatives present in the liquid fuel composition of thepresent invention is at least 1 ppmw (part per million by weight), basedon the overall weight of the liquid fuel composition. More preferably,the amount of the one or more poly(hydroxycarboxylic acid) amide saltderivatives present in the liquid fuel composition of the presentinvention additionally accords with one or more of the parameters (i) to(xx) listed below:

(i) at least 10 ppmw(ii) at least 20 ppmw(iii) at least 30 ppmw(iv) at least 40 ppmw(v) at least 50 ppmw(vi) at least 60 ppmw(vii) at least 70 ppmw(viii) at least 80 ppmw(ix) at least 90 ppmw(x) at least 100 ppmw(xi) at most 20% wt.(xii) at most 18% wt.(xiii) at most 16% wt.(xiv) at most 14% wt.(xv) at most 12% wt.(xvi) at most 10% wt.(xvii) at most 8% wt.(xviii) at most 6% wt.(xix) at most 4% wt.(xx) at most 2% wt.

Conveniently, the amount of the one or more poly(hydroxycarboxylic acid)amide salt derivatives present in the liquid fuel composition of thepresent invention may also be at least 200 ppmw, at least 300 ppmw, atleast 400 ppmw, at least 500 ppmw, or even at least 1000 ppmw.

It has been found that the use of the one or more poly(hydroxycarboxylicacid) amide salt derivatives in the liquid fuel compositions can providesignificant benefits in terms of improved lubricity of the liquid fuelcomposition, in particular when the liquid fuel composition is gasoline,relative to the liquid base fuel.

By the term “improved/improving lubricity” used herein, it is meant thatthe wear scar produced using a high frequency reciprocating rig (HFRR)is reduced.

It has additionally been found that the use of the one or morepoly(hydroxycarboxylic acid) amide salt derivatives in liquid fuelcompositions can also provide benefits in terms of engine cleanliness,in particular in terms of improved inlet valve deposit keep clean and/orinjector nozzle keep clean performance, of an internal combustion enginebeing fuelled by the liquid fuel composition of the present inventionrelative to the internal combustion engine being fuelled by the liquidbase fuel.

By the term “improved/improving inlet valve deposit keep cleanperformance”, it is meant that the weight of deposit formed on the inletvalve of the engine is reduced relative to the base fuel not containingthe one or more poly(hydroxycarboxylic acid) amide salt derivatives.

By the term “improved/improving injector nozzle keep clean performance”,it is meant that the amount of deposit formed on the injector nozzle ofthe engine is reduced as measured by the loss of engine torque.

It has additionally been found that the use of the one or morepoly(hydroxycarboxylic acid) amide salt derivatives in liquid fuelcompositions can also provide benefits in terms improved fuel economy ofan internal combustion engine being fuelled by the liquid fuelcomposition of the present invention relative to the internal combustionengine being fuelled by the liquid base fuel.

The present invention therefore also provides a method of improving thelubricity of a liquid base fuel suitable for use in an internalcombustion engine, comprising admixing one or morepoly(hydroxycarboxylic acid) amide salt derivatives with a major portionof the liquid base fuel suitable for use in an internal combustionengine; a method of improving the inlet valve deposit clean upperformance of a liquid base fuel suitable for use in an internalcombustion engine, comprising admixing one or morepoly(hydroxycarboxylic acid) amide salt derivatives with a major portionof the liquid base fuel suitable for use in an internal combustionengine; a method of improving the injector nozzle keep clean performanceof a liquid base fuel suitable for use in an internal combustion engine,comprising admixing one or more poly(hydroxycarboxylic acid) amide saltderivatives with a major portion of the liquid base fuel suitable foruse in an internal combustion engine; and, a method of improving thefuel economy performance of a liquid base fuel suitable for use in aninternal combustion engine, comprising admixing one or morepoly(hydroxycarboxylic acid) amide salt derivatives with a major portionof the liquid base fuel suitable for use in an internal combustionengine.

It has additionally been found that the use of the one or morepoly(hydroxycarboxylic acid) amide salt derivatives in liquid fuelcompositions can also provide benefits in terms improving the lubricantperformance of an internal combustion engine being fuelled by the liquidfuel composition of the present invention relative to the internalcombustion engine being fuelled by the liquid base fuel.

In particular, the improvement in the lubricant performance of theinternal combustion engine fuelled by a liquid fuel compositionaccording to the present invention can be observed by the a reduction inthe levels of sludge and varnish on specific engine parts, such assludge on rocker arm covers, cam baffles, timing chain covers, oil pans,oil pan baffles, and valve decks, and varnish on piston skirts and cambaffles.

In particular, it has been found that the use of the one or morepoly(hydroxycarboxylic acid) amide salt derivatives in a gasolinecompositions can provide benefits in terms inhibiting specific sludgeand varnish deposit formation, as measured by ASTM D 6593-07, of aninternal combustion engine being fuelled by the gasoline composition ofthe present invention relative to the internal combustion engine beingfuelled by the gasoline base fuel.

Therefore, the present invention also provides a method of improving theperformance of the lubricant of an internal combustion engine, saidmethod comprising fuelling an internal combustion engine containing theengine lubricant with a liquid fuel composition according to the presentinvention.

It has also been observed that the use of one or morepoly(hydroxycarboxylic acid) amide salt derivatives wherein the anion isa non-sulfur-containing anion in a liquid fuel composition can have theadditional advantage of improved phosphorus volatility properties of theengine lubricant of an internal combustion engine fuelled by the liquidfuel composition compared to the phosphorus volatility properties of theengine lubricant when one or more poly(hydroxycarboxylic acid) amidesalt derivatives wherein the anion is a sulfur-containing anion is usedin the liquid fuel composition.

The phosphorus volatility properties of the engine lubricant canconveniently be measured according to the phosphorus emission index(PEI) test, which is also known as the “Selby-Noack PEI test”. This testhas been described in T. W. Selby, R. J. Bosch and D.C. Fee, “ContinuedStudies of the Causes of Engine Oil, Phosphorus Volatility—Part 2”. SAE2007-01-1073, the teaching of which is hereby incorporated by specificreference. The “Selby-Noack PEI test” is similar to the “Noackprocedure” as described in ASTM D 5800, procedure C, but deviates induration (16 hours instead of 24 hours for the Noack procedure) andtemperature (250° C. for the Noack procedure). As the PEI is anapproximation of the quantity of phosphorus (mg) obtained from 1 kg offluid, it has no unit. By the term “improved phosphorus volatilityproperties”, it is meant that the PEI is lower than the PEI result it isbeing compared to.

Therefore, the present invention also provides the use of one or morepoly(hydroxycarboxylic acid) amide salt derivatives wherein the anion isa non-sulfur-containing anion in a liquid fuel composition according tothe present invention for improving the phosphorus volatility propertiesof an engine lubricant of an internal combustion engine fuelled by theliquid fuel composition compared to the phosphorus volatility propertiesof the engine lubricant when one or more poly(hydroxycarboxylic acid)amide salt derivatives wherein the anion is a sulfur-containing anion isused in the liquid fuel composition.

The present invention further provides a method of operating an internalcombustion engine, which method involves introducing into a combustionchamber of the engine a liquid fuel composition according to the presentinvention.

The one or more poly(hydroxycarboxylic acid) amide salt derivatives ofthe present invention may also be conveniently incorporated intolubricant formulations, especially engine crank case lubricantformulations.

The present invention will be further understood from the followingexamples. Unless otherwise stated, all amounts and concentrationsdisclosed in the examples are based on weight of the fully formulatedfuel composition. The examples are provided for illustration only andare not to be construed as limiting the claimed invention in any way.

EXAMPLES

In examples 1 to 41, two different commercially availablehyperdispersants have been used, the hyperdispersants werepoly(hydroxycarboxylic acid) amide salt derivatives, wherein the anionis a methyl sulphate anion, according to the present invention wereproducts available commercially from Shanghai Sanzheng Polymer Companyunder the trade designations “CH-5” and “CH-7”. Certain measuredproperties of both CH-5 and CH-7 are given in Table 1 below:

TABLE 1 Measure properties of CH-5 and CH-7 MW TBN (mgKOH/g) (ASTM D4739) N (% w) S (% w) CH-5 ~1130 1.9 0.89 0.95 CH-7 ~1050 1.9 0.82 0.86

Examples 1 to 39 and Comparative Examples A to D

The CH-5 and CH-7 hyperdispersants described above were blended into abase fuel selected from the gasoline, diesel, GTL diesel and SwedishClass I diesel base fuels described in Tables 2 and 3 below, in variousamounts.

TABLE 2 Diesel base fuels. Parameter Diesel A Diesel B^(a) Diesel C^(b)Cetane No. 52.80 >76 53.10 (ASTM D613) Density at 0.84 g/cm³ 0.78 g/cm³0.82 g/cm³ 15° C. (IP365) Flash Point 62.0° C. 104.0° C. 72.5° C. (IP34)IBP (IP123) 168.6° C. 211.0° C. 190.3° C. 10% rec. 201.3° C. 251.3° C.203.4° C. (IP123) 20% rec. 223.9° C. 262.4° C. 211.1° C. (IP123) 30%rec. 246.3° C. 273.3° C. 225.9° C. (IP123) 40% rec. 266.7° C. 285.6° C.225.9° C. (IP123) 50% rec. 281.8° C. 297.3° C. 234.2° C. (IP123) 60%rec. 293.9° C. 307.6° C. 242.2° C. (IP123) 70% rec. 306.0° C. 316.9° C.250.6° C. (IP123) 80% rec. 319.7° C. 326.9° C. 259.4° C. (IP123) 90%rec. 337.2° C. 339.1° C. 270.5° C. (IP123) 95% rec. 350.8° C. 348.6° C.279.5° C. (IP123) FBP (IP123) 362.3° C. 355.3° C. 291.6° C. Viscosity at2.74 mm²/s 3.54 mm²/s 1.94 mm²/s 40° C. (IP71) Sulphur content 8.4mg/kg^(c) <3 mg/kg^(c) <3 mg/kg^(d) Total 40.5% m/m 0.4% m/m 13.3% m/mAromatics (IP391/01/ IP548/07) ^(a)Fischer-Tropsch (GTL) derived dieselfuel ^(b)Swedish Class I diesel fuel ^(c)ISO 20884 ^(d)ISO 20846

TABLE 3 Gasoline base fuel. Parameter “Gasoline” RON (ASTM D2699) 96.00MON (ASTM D2700) 85.10 Density at 15° C. (IP365) 0.73 g/cm³ IBP (IP123)26.5° C. 10% rec. (IP123) 37.9° C. 20% rec. (IP123) 48.9° C. 30% rec.(IP123) 61.0° C. 40% rec. (IP123) 74.4° C. 50% rec. (IP123) 88.2° C. 60%rec. (IP123) 101.4° C. 70% rec. (IP123) 113.3° C. 80% rec. (IP123)127.9° C. 90% rec. (IP123) 149.2° C. 95% rec. (IP123) 164.7° C. FBP(IP123) 191.2° C. RVP *(IP394) 87.8 kPa Olefins (inc. dienes) 16.40%vol. Aromatics 28.88% vol.

To assess the lubricity of the liquid fuel compositions described above,the following test procedures were used.

The lubricity of the diesel fuel compositions was determined using theHFRR test used described in ISO 12156-1.

The lubricity of the gasoline compositions was determined by using amodified HFRR test. The modified HFRR test is based on ISO 12156-1 usinga PCS Instruments HFRR supplemented with the PCS Instruments GasolineConversion Kit, and using a fluid volume of 15.0 ml (+/−0.2 ml), a fluidtemperature of 25.0° C. (+/−1° C.), and wherein a PTFE cover is used tocover the test sample in order to minimise evaporation.

The results of the lubricity tests are given below in Table 4.

TABLE 4 HFRR Results for base fuel and fuel compositions according tothe present invention. Hyperdispersant Average HFRR Example Base Fuel(concentration) Wear Scar (μm) A* Diesel A — 366.5  1 Diesel A CH-5 (100ppmw) 344.5  2 Diesel A CH-5 (500 ppmw) 341.5  3 Diesel A CH-5 (1000ppmw) 332  4 Diesel A CH-5 (1% wt) 254  5 Diesel A CH-5 (10% wt.) 224.5 6 Diesel A CH-7 (50 ppmw) 319.5  7 Diesel A CH-7 (100 ppmw) 321.5  8Diesel A CH-7 (500 ppmw) 327.5  9 Diesel A CH-7 (1000 ppmw) 322 10Diesel A CH-7 (1% wt) 228.5 11 Diesel A CH-7 (10% wt.) 214.5 B* Diesel B— 624 12 Diesel B CH-5 (500 ppmw) 335 13 Diesel B CH-5 (1000 ppmw) 36514 Diesel B CH-5 (1% wt) 281.5 15 Diesel B CH-5 (10% wt.) 246.5 16Diesel B CH-7 (500 ppmw) 427.5 17 Diesel B CH-7 (1000 ppmw) 386.5 18Diesel B CH-7 (1% wt) 304 19 Diesel B CH-7 (10% wt.) 216 C* Diesel C —624.5 20 Diesel c CH-5 (100 ppmw) 442.5 21 Diesel C CH-5 (1000 ppmw)376.5 22 Diesel c CH-5 (1% wt) 289.5 23 Diesel C CH-5 (10% wt.) 228.5 24Diesel c CH-7 (500 ppmw) 471 25 Diesel C CH-7 (1000 ppmw) 335 26 Dieselc CH-7 (1% wt) 255.5 27 Diesel C CH-7 (10% wt.) 209 D* Gasoline — 907 28Gasoline CH-5 (50 ppmw) 630.5 29 Gasoline CH-5 (100 ppmw) 412.5 30Gasoline CH-5 (500 ppmw) 308.5 31 Gasoline CH-5 (1000 ppmw) 346 32Gasoline CH-5 (1% wt) 229.5 33 Gasoline CH-5 (10% wt.) 202.5 34 GasolineCH-7 (50 ppmw) 861.5 35 Gasoline CH-7 (100 ppmw) 639 36 Gasoline CH-7(500 ppmw) 358 37 Gasoline CH-7 (1000 ppmw) 347 38 Gasoline CH-7 (1% wt)206.5 39 Gasoline CH-7 (10% wt.) 206.5 *Not according to the presentinvention.

As can be seen from the results in Table 4, a reduced wear scar isobserved in the HFRR test for the fuel compositions (both gasoline anddiesel fuel compositions) containing the CH-5 and CH-7 hyperdispersantscompared to the base fuel, which represents an improvement in lubricityof the fuels containing the hyperdispersant compared to the base fuel.

Example 40

Inlet valve deposit (IVD) keep clean tests were performed for twogasoline compositions prepared by blending a base gasoline as describedin Table 5 below with 400 ppmw and 1000 ppmw of the CH-5hyperdispersant.

TABLE 5 Gasoline base fuel. Parameter RON (ASTM D2699) 98.9 MON (ASTMD2700) 87.3 Density at 15° C. (IP365) 0.7758 g/cm³ IBP (IP123) 33.3° C.10% rec. (IP123) 56.4° C. 20% rec. (IP123) 78.2° C. 30% rec. (IP123)96.8° C. 40% rec. (IP123) 109.3° C. 50% rec. (IP123) 118.6° C. 60% rec.(IP123) 127.0° C. 70% rec. (IP123) 136.4° C. 80% rec. (IP123) 147.5° C.90% rec. (IP123) 161.4° C. 95% rec. (IP123) 171.8° C. FBP (IP123) 202.9°C. RVP (IP394) 62.2 kPa Olefins (inc. dienes) 7.44% vol. Aromatics49.78% vol.

The IVD test was performed in a Toyota 2.0 L 3S-FE bench engine usingthe CEC-F-05-A-93 M102E operating cycle modified by BMEP to the torqueconditions detailed in Table 6 below. The Toyota engine has beenmodified to concurrently run two fuel systems, one fuelling cylinders 1and 2 and a second fuelling cylinders 3 and 4. The engine starts withclean valves and combustion chamber and is run for 69 hr on the testfuels. At the end of the 69 hours the engine is stripped, the valvesweighed to determine the level of deposits.

TABLE 6 Engine test cycle details for Toyota DF engine Coolant Oil outStage Stage Engine Torque out temp temp No time (s) speed (rpm) (Nm) (°C.) (° C.) 1 30 800 0 90 97 2 60 1300 26 90 97 3 120 1850 28 90 97 4 603000 30 90 97

The gasoline containing 400 and 1000 ppmw respectively of CH-5 wastested in the Toyota 3S-FE dual fuelled engine with the 400 ppmw CH-5gasoline test blend in cylinders 1 and 2 and the 1000 ppmw CH-5 gasolinetest blend in cylinders 3 and 4.

The average weight of the inlet valve deposits for cylinders 1 and 2 was194.6 mg and for cylinders 3 and 4 was 130.0 mg. An average level ofdeposit observed with a gasoline containing no additives in a 69 hourtest is typically about 200 mg.

Example 41

The injector nozzle keep clean performance of the CH-5 hyperdispersantin diesel fuel was assessed using the CEC SG-F-098 test procedure. Thediesel fuel used in the test procedure contained 300 ppmw of the CH-5hyperdispersant. In the test, up until 24 hours no power loss wasobserved and at 32 hours a power loss equating to 3% was observed. Atthis point the equivalent power loss for the reference fuel was 9%.

Preparation of Non-Sulfur-Containing Poly(Hydroxycarboxylic Acid) AmideSalt Derivatives Example E

8 gram of the poly(hydroxycarboxylic acid) amide salt derivativecommercially available from Shanghai Sanzheng Polymer Company under thetrade designation “CH-5” was dissolved in 140 ml of dichloromethane(DCM) whilst stirring. The resultant mixture was further diluted with110 ml DCM and added to a separation funnel containing 250 ml of 1M KOHsolution.

The funnel was shaken and allowed to stand until there was clearseparation between the two layers. The organic bottom layer wascollected and added to 250 ml of fresh 1M KOH in a separation funnel.Again, the organic bottom layer was collected, dried over MgSO₄ andconcentrated in vacuo. About 6 gram of poly(hydroxycarboxylic acid)amide salt derivative wherein the anion X^(q−) is OH was obtained.

The obtained poly(hydroxycarboxylic acid) amide salt derivative had aTBN content of 7.4 mg·KOH/g (according to ASTM D 4739).

Example F

The “CH-5” product (see Example E) was ion-exchanged with a sodiumsalicylate (available from Sigma-Aldrich Chemical Company, Gillingham,United Kingdom) in a ion-exchange column, whilst using 1:3 MeOH:CHCl₃ asan eluent.

To this end, a column was prepared using 500 gram Dowex 1×8 ion-exchangeresin (200-400 mesh, strongly basic Cl⁻ form; CAS nr [69011-19-4]) whichwas washed in 1 l of deionised water. The washed Dowex resin was thenloaded as a suspension onto a column using 1 l of 1:1 MeOH:de-ionisedwater. The resin was then washed with 4 bed volumes of 1:1methanol/de-ionised water and loaded with a 30 wt. % solution of thesodium salicylate salt of in a small amount of MeOH.

Subsequent polarity change of the resin was done in the following order:2×4 bed volumes of 1:1 MeOH/de-ionised water; 1×4 bed volumes of MeOH; 4bed volumes of 3:1, then 1:1, then 1:3 of MeOH:chloroform.

220 gram of the “CH-5” product was dissolved in a minimum amount ofeluent (1:3 MeOH:chloroform) and loaded onto the column. The column waseluted, whilst following the elution by means of thin layerchromatography using appropriate staining techniques. The eluent wascollected and concentrated in vacuo to dryness to yield about 200 gramof poly(hydroxycarboxylic acid) amide salt derivative wherein the anionX^(q−) is salicylate.

The obtained poly(hydroxycarboxylic acid) amide salt derivative had aTBN content of 8.2 mg·KOH/g (according to ASTM D 4739).

Example G

Similar to Example F, a poly(hydroxycarboxylic acid) amide saltderivative was obtained wherein the anion X^(q−) is a phenate. To thisend sodium phenoate (available from Sigma-Aldrich Chemical Company,Gillingham, United Kingdom) was used.

The obtained poly(hydroxycarboxylic acid) amide salt derivative had aTBN content of 8.5 mg·KOH/g (according to ASTM D 4739).

Example H

Similar to Example F, a poly(hydroxycarboxylic acid) amide saltderivative was obtained wherein the anion X^(q−) is an oleate. To thisend sodium oleate (available from Sigma-Aldrich Chemical Company,Gillingham, United Kingdom) was used.

The obtained poly(hydroxycarboxylic acid) amide salt derivative had aTBN content of 7.9 mg·KOH/g (according to ASTM D 4739).

Example I

Similar to Example F, a poly(hydroxycarboxylic acid) amide saltderivative was obtained wherein the anion X^(q−) is an acetate. To thisend sodium acetate (available from Sigma-Aldrich Chemical Company,Gillingham, United Kingdom) was used.

The obtained poly(hydroxycarboxylic acid) amide salt derivative had aTBN content of 8.5 mg·KOH/g (according to ASTM D 4739).

Engine Lubricant Performance

The performance of the crankcase lubricant of an engine fuelled using aliquid fuel composition according to the present invention was assessedusing the Sequence VG test, ASTM D 6593-07.

Two separate poly(hydroxycarboxylic acid) amide salt derivatives wereassessed using in the Sequence VG tests. The base fuel used for bothpoly(hydroxycarboxylic acid) amide salt derivatives was an ASTM VG basefuel.

Fuel “Base” is ASTM VG base fuel.

Fuel “F-A” is “Base”+500 ppmw of “CH-5”.

Fuel “F-B” is “Base”+200 ppmw of Example F.

Lubricant “L-A” is an SF grade lubricant.

Lubricant “L-B” is a SL/CF grade lubricant.

The results of the Sequence VG tests are provided in Table 7 below. The“merit” rating used in the results is on a scale of 0 to 10, with 10representing the rating of the condition of the component when new, anda single number increase in the “merit” rating represents a reduction inthe sludge or varnish by half.

TABLE 7 Sequence VG test results Final Original Unit Results AverageRocker Average Average Engine Cover Engine Piston Sludge Sludge VarnishSkirt Example Fuel Lubricant (merits) (merits) (merits) Varnish 42 F-AL-A 9.71 9.79 9.82 9.69 J* Base L-A 7.88 9.42 8.99 7.60 43 F-B L-B 9.789.74 9.92 9.99 K* Base L-B 9.28 9.41 9.28 8.26 44 F-B L-B 9.80 9.73 9.9810.00 *Comparative TS 7750

As can clearly be seen from the results given in Table 7 above, the useof poly(hydroxycarboxylic acid) amide salt derivatives in the gasolinecompositions results in a significant improvement in the performance ofthe lubricant in terms of inhibition of sludge and varnish depositformation.

1. A liquid fuel composition comprising: a) a base fuel suitable for usein an internal combustion engine; and b) one or morepoly(hydroxycarboxylic acid) amide salt derivatives having formula(III):[Y—CO[O-A-CO]_(n)-Z_(r)-R⁺]_(m)pX^(q−)  (III) wherein Y is hydrogen oran optionally substituted hydrocarbyl group, A is a divalent optionallysubstituted hydrocarbyl group, n is from 1 to 100, m is from 1 to 4, qis from 1 to 4 and p is an integer such that pq=m, Z is an optionallysubstituted divalent bridging group which is attached to the carbonylgroup through a nitrogen atom, r is 0 or 1, R⁺ is an ammonium group andX^(q−) is an anion.
 2. The liquid fuel composition of claim 1 whereinthe amount of the one or more poly(hydroxycarboxylic acid) amide saltderivatives present in the liquid fuel composition is at least 1 ppmw,based on the overall weight of the liquid fuel composition.
 3. Theliquid fuel composition of claim 2 wherein the amount of the one or morepoly(hydroxycarboxylic acid) amide salt derivatives present in theliquid fuel composition is in the range of from 10 ppmw to 20% wt, basedon the overall weight of the liquid fuel composition.
 4. The liquid fuelcomposition of claim 1 wherein the anion, X^(q−), is anon-sulphur-containing anion, preferably the anion, X^(q−), is selectedfrom anions derived from compounds containing a carboxylic acid group,anions derived from compounds containing a hydroxyl group, nitrogenbased anions, phosphorus based anions, and mixtures thereof.
 5. Theliquid fuel composition of claim 4 wherein the amount of the one or morepoly(hydroxycarboxylic acid) amide salt derivatives present in theliquid fuel composition is at least 1 ppmw, based on the overall weightof the liquid fuel composition.
 6. The liquid fuel composition of claim5 wherein the amount of the one or more poly(hydroxycarboxylic acid)amide salt derivatives present in the liquid fuel composition is in therange of from 10 ppmw to 20% wt, based on the overall weight of theliquid fuel composition.
 7. The liquid fuel composition of claim 1wherein the anion, X^(q−), is a sulphur-based anion, preferably theanion, X^(q−), is selected from sulphate, sulphonate and mixturesthereof.
 8. The liquid fuel composition of claim 7 wherein the amount ofthe one or more poly(hydroxycarboxylic acid) amide salt derivativespresent in the liquid fuel composition is at least 1 ppmw, based on theoverall weight of the liquid fuel composition.
 9. The liquid fuelcomposition of claim 8 wherein the amount of the one or morepoly(hydroxycarboxylic acid) amide salt derivatives present in theliquid fuel composition is in the range of from 10 ppmw to 20% wt, basedon the overall weight of the liquid fuel composition.
 10. The liquidfuel composition of claim 7 wherein the one or more of thepoly(hydroxycarboxylic acid) amide salt derivatives have a sulphurcontent in the range of from 0.1 to 2.0 wt. %, based on the total weightof said poly(hydroxycarboxylic acid) amide salt derivatives.
 11. Theliquid fuel composition of claim 1 wherein the one or more of thepoly(hydroxycarboxylic acid) amide salt derivatives have a TBN (totalbase number) value of less than 10 mg·KOH/g.
 12. The liquid fuelcomposition of claim 3 wherein the one or more of thepoly(hydroxycarboxylic acid) amide salt derivatives have a TBN (totalbase number) value of less than 10 mg·KOH/g.
 13. The liquid fuelcomposition of claim 4 wherein the one or more of thepoly(hydroxycarboxylic acid) amide salt derivatives have a TBN (totalbase number) value of less than 10 mg·KOH/g.
 14. The liquid fuelcomposition of claim 7 wherein the one or more of thepoly(hydroxycarboxylic acid) amide salt derivatives have a TBN (totalbase number) value of less than 10 mg·KOH/g.
 15. The liquid fuelcomposition of claim 1 wherein the base fuel is a gasoline.
 16. Theliquid fuel composition of claim 1 wherein the base fuel is a dieselfuel.
 17. A method of operating an internal combustion engine, whichmethod comprises introducing into a combustion chamber of the engine aliquid fuel composition of claims
 1. 18. A method of operating aninternal combustion engine, which method comprises introducing into acombustion chamber of the engine a liquid fuel composition of claims 3.19. A method of operating an internal combustion engine, which methodcomprises introducing into a combustion chamber of the engine a liquidfuel composition of claims
 4. 20. A method of operating an internalcombustion engine, which method comprises introducing into a combustionchamber of the engine a liquid fuel composition of claims 7.